Currently, the main sample pretreatment methods for forensic toxic analysis are liquid-liquid extraction （LLE） and solid-phase extraction （SPE）. As a simple, convenient, and low-cost LLE method, dispersion liquid-liquid microextraction （DLLME） has high enrichment factor and good extraction efficiency, and therefore has attracted the attention of many researchers in the field of toxicology analysis in recent years. As a multi-functional microextraction method, DLLME has been widely used in the analysis of pesticides, sleeping sedatives, drugs and heavy metal poisons in forensic toxic analysis. Meanwhile, it can also be used in combination with such a variety of analytical instruments as gas chromatography-electron capture detectors （GC-ECD）, high performance liquid chromatography-diode array detectors （HPLC-DAD）. As a sample pretreatment method, DLLME has the advantages of simple operation, less use of organic solvent, reliable results and good reproducibility, thus can meet the requirements of modern court toxic analysis.
Forensic Toxicology ; Liquid Phase Microextraction ; Reproducibility of Results ; Solid Phase Extraction ; Solvents

A rapid and sensitive liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method for quantification of sitagliptin in human plasma and urine had been developed. This method was applied to the pharmacokinetics study of sitagliptin tablet after single- and multiple-dosing in Chinese population. Plasma samples were prepared by a liquid-liquid extracted method, and urine samples were diluted. Compounds were analyzed by multiple reaction monitoring (MRM) mode with a electrospray ionization (ESI) interface. Mobile phase consisted of methanol and water (85 : 15, v/v). The linear concentration range of calibration curve was 0.5-1 000 ng.mL-1. and 0.2-100 µg.mL , intra-run/between-run accuracy was 98.98%-103.69% and 97.63%-102.29%, intra-run/between-run precision was <5.51% and 4.26% for plasma and urine sample, respectively. The stability of sitagliptin stock solution was tested for 55 days at -30 °C. Sitagliptin was stable when stored under the following conditions: 24 hours in the autosampler after sample preparation; 24 hours at room temperature, after 3 freeze and thaw cycles (from -30 °C to room temperature), 40 days at -30 °C for plasma and urine samples. The absolute recovery in plasma was 71.1%, and no matrix effect was founded. This method was proved simple, specific, sensitive, rapid and suitable for pharmacokinetics study of sitagliptin in human being.
Calibration ; Chromatography, Liquid ; Humans ; Liquid-Liquid Extraction ; Sitagliptin Phosphate ; blood ; pharmacokinetics ; urine ; Tandem Mass Spectrometry

Suitable pretreatment of biological samples can truly reflect the role of law of the measured components played in the body and will provide experimental evidence for the studies on metabolic process, material basis of efficacy, mechanism of action, pharmacology, toxicology and the others. Biological samples include blood, urine, hair, tears, etc. There are also many samples processing methods, such as the direct protein precipitation, liquid-liquid extraction and solid phase extraction and so on. These methods could be used alone or combined.
Animals ; Body Fluids ; chemistry ; Chemical Precipitation ; Chemistry Techniques, Analytical ; methods ; Humans ; Liquid-Liquid Extraction ; Proteins ; isolation & purification ; Solid Phase Extraction

The high prevalence of pediculosis capitis, commonly known as head lice (Pediculus humanus capitis) infestation, has led to the preparation of a community-based pediculicidal ointment, which is made of common household items and the extract of Tinospora crispa stem. The present study aimed to evaluate the safety, efficacy, and physicochemical characteristics of the T. crispa pediculicidal ointment. The physicochemical properties of the ointment were characterized, and safety was determined using acute dermal irritation test (OECD 404), while the efficacy was assessed using an in vitro pediculicidal assay. Furthermore, the chemical compounds present in T. crispa were identified using liquid-liquid extraction followed by ultra-performance liquid chromatography quadruple time-of-flight mass spectrometric (UPLC-qTOF/MS) analysis. The community-based ointment formulation was light yellow in color, homogeneous, smooth, with distinct aromatic odor and pH of 6.92±0.09. It has spreadability value of 15.04±0.98 g·cm/sec and has thixotropic behavior. It was also found to be non-irritant, with a primary irritation index value of 0.15. Moreover, it was comparable to the pediculicidal activity of the positive control Kwell®, a commercially available 1% permethrin shampoo (P>0.05), and was significantly different to the activity of the negative control ointment, a mixture of palm oil and candle wax (P<0.05). These findings suggested that the community-based T. crispa pediculicidal ointment is safe and effective, having acceptable physicochemical characteristics. Its activity can be attributed to the presence of compounds moupinamide and physalin I.
Chromatography, Liquid ; Family Characteristics ; Hydrogen-Ion Concentration ; In Vitro Techniques ; Lice Infestations ; Liquid-Liquid Extraction ; Odors ; Pediculus* ; Permethrin ; Prevalence ; Tinospora*

This study describes the development of an analytical method to determine radotinib levels in human plasma using high performance liquid chromatography (HPLC) coupled with triple quadrupole tandem mass spectrometry (MS/MS) for pharmacokinetic application. Plasma samples were sequentially processed by liquid-liquid extraction using methyl tert-butyl ether, evaporation, and reconstitution. Analytes were separated and analyzed using HPLC-MS/MS in selected reaction monitoring mode, monitoring the specific transitions of m/z 531 to 290 for radotinib and m/z 409 to 238 for amlodipine (internal standard). The HPLC-MS/MS analytical method was validated with respect to selectivity, linearity, sensitivity, accuracy, precision, recovery, and stability. Calibration curves were linear over a concentration range 5–3,000 ng/mL with correlation coefficients (r) > 0.998. The lower limit of quantification for radotinib in plasma was 5 ng/mL. The accuracy and precision of the analytical method were acceptable within 15% at all quality control levels. This method was suitable to determine radotinib levels in human plasma because of its simplicity, selectivity, precision, and accuracy.
Amlodipine ; Calibration ; Chromatography, Liquid ; Ether ; Humans* ; Liquid-Liquid Extraction ; Mass Spectrometry* ; Methods* ; Plasma* ; Quality Control ; Tandem Mass Spectrometry

OBJECTIVE: To develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) screening method for 45 poisonous alkaloids in blood. METHODS: Identification was based on the compound's retention time and two precursor-to-production transitions. The method involved a liquid-liquid extraction (LLE) followed by LC-MS/MS with multiple-reaction monitoring (MRM). When 1 mL of blood was extracted with diethyl ether at pH = 9.2 with SKF525A as the internal standard, the target compounds were analyzed with LC-MS/MS in the positive ionization mode. RESULTS: The target alkaloids had good linearity (r>0.995 1), both the intra-day precision and inter-day precision being less than 14.77%. The limits of detection ranged from 0.05 to 25 ng/mL in blood. CONCLUSION The method is selective and sensitive in detecting poisonous alkaloids with a total running time of 12 minutes; therefore it was successfully applied to some actual cases of suspected alkaloids poisoning.
Alkaloids/chemistry* ; Chromatography, Liquid/methods* ; Forensic Medicine ; Humans ; Liquid-Liquid Extraction ; Mass Spectrometry ; Sensitivity and Specificity ; Tandem Mass Spectrometry/methods*

We developed a simple, sensitive, and effective ultra-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) method with an electrospray ionization (ESI) interface in multiple reaction monitoring (MRM) and positive ion modes to determine diazepam concentrations in human plasma using voriconazole as an internal standard (IS). Diazepam and IS were detected at transition 285.2→193.1 and 350.2→127.1, respectively. After liquid-liquid extraction (LLE) using 1.2 ml of ethyl acetate:n-hexane (80:20, v/v), diazepam and IS were eluted on a Phenomenex Cadenza CD-C18 column (150 × 3.0 mm, 3 µm) with an isocratic mobile phase (10 mM ammonium acetate in water:methanol [5:95, v/v]) at a flow rate of 0.4 mL/min. The peak retention time was 2.32 min for diazepam and 2.01 min for IS, respectively. The lower limit of quantitation (LLOQ) was 0.5 ng/mL (S/N > 10) using 50 µL of plasma, and no interferences were observed in chromatograms. Our analytical method was fully validated and successfully applied to a bioequivalence study of two formulations of diazepam in healthy Korean volunteers.
Ammonium Compounds ; Diazepam* ; Humans* ; Liquid-Liquid Extraction ; Mass Spectrometry ; Methods* ; Plasma* ; Therapeutic Equivalency* ; Volunteers ; Voriconazole

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantification of donepezil in human plasma. Donepezil and donepezil-D4 were extracted from human plasma by liquid-liquid extraction using a mixture of hexane and ethyl acetate (70:30 v/v). The extracted samples were analyzed using a Thermo Hypersil Gold C18 column with 5% acetic acid in 20 mM ammonium acetate buffer (pH 3.3) and 100% acetonitrile as a mobile phase with the 60:40 (v:v) isocratic method, at a flow rate of 0.3 mL/min. The injection volume was 3 µL, and the total run time was 3 min. Inter- and intra-batch accuracies ranged from 98.0% to 110.0%, and the precision was below 8%. The developed method was successfully applied to the quantification of donepezil in human plasma. The mean (standard deviation) maximum concentration and the median (range) time to maximum concentration were 8.6 (2.0) ng/mL and 2.0 h (1.0~5.0 h), respectively, in healthy Koreans after oral administration of 5 mg donepezil.
Acetic Acid ; Administration, Oral ; Ammonium Compounds ; Humans ; Liquid-Liquid Extraction ; Mass Spectrometry ; Methods ; Plasma

Objective: A method for the determination of acetochlor and its metabolites in urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established. Methods: After cleaned-up by a HLB extraction cartridges, the urine was eluted with 1% acetic acid acetonitrile solution. The target compounds were separated by ACQUITY UPLC®HSS T3 Column (2.1 mm×100 mm×1.8 μm) by using 1% formic acid solution and acetonitrile as mobile phase with gradient elution program, and analyzed in positive electrospray ionization mode by liquid chromatography tandem mass spectrometry. Results: All the target compounds showed good linear relationships in the range of 1-50 μg/L, and the correlation coefficients (r) were higher than 0.997. The recoveries rates at three different spiked levels for all target compounds in blank matrices were 107.6%-129.1%, and the relative standard deviations (RSD) were 1.5%-9.9% (n=6) . The limits of detection and quantitation of the method were 0.04-0.11 μg/L and 0.15-0.42 μg/L, respectively, and target substances were detected in all urine samples from occupational exposure workers to acetochlor. Conclusion: This method is suitable for rapid screening and analysis of acetochlor and metabolites in urine with the advantages of accuracy, rapidity, simplicity, high sensitivity and good specificity.
Acetonitriles ; Chromatography, High Pressure Liquid ; Chromatography, Liquid ; Humans ; Solid Phase Extraction ; Tandem Mass Spectrometry ; Toluidines

Objective To investigate the maximum allowable deviation of ion abundance ratios of characteristic fragment ions in common drugs （poisons） in blood by gas chromatography-mass spectrometry （GC-MS） method. Methods Four common drugs （poisons） （dichlorvos, phorate, diazepam and estazolam） were detected by GC-MS full scan mode after liquid-liquid extraction in two laboratories and under three chromatographic conditions. The deviations of ion abundance ratios of the four common drugs （poisons） in marked blood samples with concentrations of 0.5, 1.0, 2.0, 5.0 and 10.0 μg/mL were analyzed. At the same time, the false negative rates of ion abundance ratios were analyzed when the mass concentration was limit of detection （LOD）, 2LOD, limit of quantitation （LOQ） and 2LOQ, and the false positive rates of ion abundance ratios were analyzed with blank blood samples. Results Under the two laboratories, four common drugs （poisons） and three kinds of chromatography conditions, the differences in deviations of the ion abundance ratios of marked blood samples were not statistically significant （P>0.05）. More than 95% of the absolute deviations of the ion abundance ratios of the marked blood samples were within the range of ±10%, and more than 95% of the relative deviations were within the range of ±25%. In cases of low concentration （concentration less than 2LOQ） or low signal to noise ratio （3-15）, the false negative rate was less than 5% and the false positive rate was 0% when the relative deviation was greater than 50%. Conclusion The absolute deviations of ion abundance ratios of four common drugs （poisons） in marked blood samples are advised to have a determination range within ±10%, and the determination range of relative deviations within ±25%.
Gas Chromatography-Mass Spectrometry ; Humans ; Ions/chemistry* ; Limit of Detection ; Liquid-Liquid Extraction ; Poisons/blood*